Field of the Invention
The present invention relates to an optical wheel device and a projection system (projector) which includes the optical wheel device.
Description of the Related Art
In these days, data projectors are used on many occasions as an image projection system which projects images including an image of a monitor of a personal computer and a video image, as well as images based on image data which is stored on a memory card on to a screen.
In these data projectors, light emitted from a light source is caused to converge to a micromirror display device called a DMD (Digital Micromirror Device) or a liquid crystal panel so that a full-color image is displayed onto a screen.
In addition, the application of such projectors is expanding widely from commercial presentation to domestic use as video equipment including personal computers, DVD players and the like has been used generally.
Conventionally, the mainstream of these projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made many developments and proposals on light source apparatuses which use, as a light source, a plurality of semiconductor light emitting elements such as laser diodes and which include a plurality of optical parts such as lenses, mirrors and the like in association with the use of such semiconductor light emitting elements.
For example, a light source unit has been proposed which includes an excitation light source which emits light of a blue wavelength range by using a laser diode, and an optical wheel (a rotary plate) which has a layer of luminescent material which absorbs light emitted from the excitation light source to convert it into visible light and which is driven to rotate by a motor, and a projector which includes this light source unit has been proposed.
Japanese Unexamined Patent Publication (KOHKAI) No. 2004-197922 (JP-2004-197922 A) discloses a rotary disc like a color wheel which can remove vibrations thereof effectively by containing a curable liquid in a dish-shaped container which is provided in the rotary disc to balance the weight of the rotary disc when it is rotating to thereby suppress the vibrations thereof.
However, JP-2004-197922 A above proposes the configuration in which the dish-shaped container is provided to connect the color wheel to a distal end of a rotating shaft, and an adhesive is poured into the container. Due to the provision of the container, in disposing a collective lens which collects efficiently excitation light to an excitation light source side of the color wheel or the like, the collective lens has to be disposed while ensuring spaces for a lens unit and the container.
Consequently, it is difficult to shorten a distance between the collective lens and the color wheel, resulting in a problem that the wheel device has to be made large in size.